1. Field of the Invention
The present invention relates, in general, to a device for sensing a sudden stop of a machine such as a car or an industrial robot and, more particularly, to a sudden stop sensing device capable of quickly and precisely sensing a sudden stop of a car or an actuating arm of an industrial robot and outputting an electric signal informing a driver or an operator of such a sudden stop.
2. Description of the Prior Art
As well known to those skilled in the art, several types of devices for sensing a sudden stop of machines such as cars or industrial robots are proposed and practically used.
A known sudden stop sensing device for machines is shown in FIG. 1A. The known sensing device of FIG. 1A is comprised of a sealed tank 101 which is almost half filled with mercury 102. Two electrodes are set on one side wall of the tank 101 in such a manner that one electrode 103 is positioned under the horizontal normal level of the mercury 102, thus being always immersed in the mercury 102, and the other electrode 103' is positioned above the normal level of the mercury 102, thus being not immersed in the mercury 102. In the event of a sudden stop of a car or an industrial robot, the mercury 102 inertially leans to one side, thus causing the mercury level to be inclined and bringing the two electrodes 103 and 103' into a conductive state as shown by the phantom line of FIG. 1. When the two electrodes 103 and 103' are brought into such a conductive state as described above, an electric current flows in the sensing device, thus causing the device to generate a sudden stop signal.
FIG. 1B shows the construction of a known sudden stop sensing device for machines such as cars or industrial robots in accordance with another embodiment. The sensing device of FIG. 1B is comprised of a sealed tank which is provided with a slope therein. Two electrodes 103 and 103' are set on the side wall of the tank at a position around the highest edge of the slope, while a steel ball 104 is movably laid on the slope. The ball 104 normally rests on the lowermost edge of the slope by its own weight. However, in the event of a sudden stop of a car or a robot, the ball 104 inertially rolls on the slope, thus reaching the highest edge of the slope and coming into common contact with the two electrodes 103 and 103'. In such a case, an electric current flows in the sensing device and generates a sudden stop signal.
However, the above sudden stop sensing devices have the following problems. First, the sensitivity of the devices cannot be adjusted in accordance with the use of the devices. Second, it is almost impossible to give an operational deflection to the sensing devices. In addition, the sensing devices may be unexpectedly operated by normal operational vibrations or rotating motions of machines, thus having a reduced operational reliability.
Particularly, the sensing device with mercury may cause environmental pollution and may result in a serious hygienic problem for users. Another problem experienced in the known sensing devices is that it is impossible to measure the extent of a sudden stop.